Method of treating metallic bodies on one surface



June 4, 1929.

METHOD OF TREATING METALLIC BODIES ON ONE SURFACE N. H. SCHERMER El' ALFiled Oct. 24, 1927 I attoznui Patented dans 4, i929.,

miami NATHAN E. SCHERMER AND CHARLES Gr. HEILMAN, OF HIGHLAND TABLE,MICHIGAN.

METHODy 0F TREATING METALLIC BODIES ON ONE SURFACE.

Application led October 24, 1927. Serial N0. 228,437.

The present invention pertains to a novel method of modifying onesurface of a metallic body while retaining the other surface inapproximately its original condition. Such a method is useful anddesirable in cases where the modifying treatment, if applied throughoutthe metallic body, would render it unfit for certain of its intendedfunctions or for certain operations subsequently to be performedthereon. A. specific example of such an instance is the case of a brakedrum which requires one high .carbon surface, while if the drum iscarburized throughout, it will become too brittle for operations whichmay later be performed thereon.

Considering this example further, the metallic bodies are carburized enone surface while still in the form of disks or sheets prior to theshaping operations. The disks are arranged face to face in pairs, andthese pairs are packed with carburizing material in a container in sucha manner that each pair is entirely surrounded by this substance, butthe members `thereof have only their noncontacting surfaces exposed tothe hardening material. The container is placed in an oven according tothe usual carburizing process and may be lcooled in view of the desiredresulting hardness or the nature of the metal under treatment. After thecontainer has been removed from the oven and the metallic bodies arecooled, they are stamped or otherwise treated to take the shape of abrake drum. The carburized surface of the body constitutes the wearingsurface of the drum while the uncarburized surface of the metal isdisposed on the other surface of the drum where carburizing is notnecessary.

The invention is fully disclosed by way of example in the followingdescription and in the accompanying drawing, in whichy Figure l shows aplan View and an edge view of the disk to be treated;

Fig: 2 is a plan view of the 'container partly broken away;

Fig. 3 is a transverse section of-the container showing the bodiesembedded in the hardening material;

Fig. 4 is an edge view of one of the carburized disks, partly brokenaway fto show the e`ect of the treatment;

Fig. 5 is a plan view of the drum formed from the treated disk, partlybroken away to show the nature of the treatment; and

Fig. 6 is a transverse section of the drum.

Reference to these views will now be made by use of like characterswhich are employed to designate corresponding parts throughout.

As an example of the applicability of this process, we have chosen abrake drum to be formed from a sheet or disk 1 of suitable metal. Asalready indicated, it is desired to carburize only one surface of thedisk and to leave the other surface unmodied. lilith this object inview, the disks are arranged in pairs 2 wherein the members of each pairare placed face to face and in marginal coincidence as clearly shown inFigure 3. In this condition-the pairs of disks are e/mbedded in asuitable carburizing material 3 contained in a receptacle 4, but it isto be noted that the pairs themselves are spaced from one another withthe result that only the non-contacting surfaces of the members of eachpair are exposed to the carburizing medium. 'There maybe some iiow ofgas to the contacting faces, particularly at the edges-but not suficientto produce any appreciable carburizing.

The container is equipped with a cover 5 and placed in an oven where itis heated according to existing processes of carburizing metal. Afterthe completion of this operation, each body is carburized only at thesurface which has been exposed to the substance 3 as indicated by thenumeral 6 in Figures 4, 5 and 6, and the concealed surface will retainsubstantially its original character.

The bodies l are now shaped, as by stamping for example, into brakedrums 7, and this operation is performed in such a manner that thecarburized surface 6 will constitute the wear surface of the drum. rlheretention of the remaining surface 8 in substantially its originalcondition is beneficial to the shaping operation, and if the body l werecarburized throughout, it would be more difficult te shape.

After this operation the metal may be further hardened by heating andquenching, if desired, although carburizing alone considerably improvesthe wearing qualities and increases the hardness.

Although the invention has been illustrated and described in connectionwith a brake drum, this disclosure of the invention is onlyillustrative, and it will be understood that the invention is applicablegenerally to the treatment of one surface of a body te the exclusion ofthe other surface, by methods other than carburizing, and that departurefrom the present disclosure may be made in accordance with the scope ofthe invention as indicated by the appended claims.

lVhat we claim is:

l. A method of hardening one surface of metal blanks suitable forbending, consisting in arranging such vuntreated blanks in spaced.pairs, with the members of each pair in juxtaposition relative to eachother and in direct contact with each other to conceal one surface ofeach, whereby when exposed to a hardening medium only one surface ofeach is hardened.

2. A method of hardening one surface of metal blanks preparatory tobending, consisting in arranging such untreated blanks in i spacedpairs, with the members of each pair 1n superposed contacting relationwith each other to conceal one surface of each whereby when exposed to ahardening medium only one surface of each is hardened.

Y 3. A method of carburizing one surface of metal blanks suitable forbending, consisting in arranging such untreated blanks in spaced pairs,with the members of each pair in juxtaposition relative to each otherand in direct contact with each other to conceal v one surface of eachwhereby when exposed to a carburizing medium only one surface of eachblank is carburized.

4. A method of hardening one surface of metal blanks suitable forbending, consisting in arranging such untreated blanks in spaced pairsand in embedding such pairs in a .hardening medium with thc .members ofeach pair in superposed contacting relation' with eachother to concealone surface of each whereby only onesurface of each is hardened.

In testimony whereof we affix our slgnatures.

NATHAN H. SCHERMER. CHARLES G. HEILMAN.

